Film rewinding system



March 2, 1954 Filed Jan. 27, 1951 B. F. R-YAN 2,670,904

FILM REWINDING SYSTEM 2 Sheets-Sheet 1 INVENTOR.

lrraixviy March 2, 1954 Y N 2,670,904

FILM REWINDING SYSTEM Filed Jan, 27, 1951 2 Sheets-Sheet 2 9} Q 3 I I I v Q s J N "x o W INVENTOR. .Byeo/v/f Pym/ & irrae/viy ing of a sound sequence and Patented Mar. 2, 1954 Byron F. Ryan,

Van Nuys, Calif., assignor to Warner Bros. Pictures, Inc., corporation of Delaware Application January 27,1951, Serial No.

Burbank, Califi, a

Claims. (CI. 24245) This invention relates to motion picture film apparatus, and particularly to a film rewind a composite sound track. In recording operation, there are generally several rehearsals before the final take. Frequently, the reproducers are stopped during the rerecordthe film rewound for repetition of the rehearsal or take. Thus, several sound films must be returned to their starting points, or completely rewound.

when de-energized.

{The principal object of the invention, therefore, is to facilitate the rewinding of motion picfilm. Another object of an improved rewind film. V e

v A further object of the invention is to provide a rewind system for motion. picture film which the invention is to provide system for motion picture will rapidly rewind the film without introducing undue tension in the film as it is taken from the supply reel.

" producer embodying the invention.

, motor drive system for the film reproducer includes a. frame Although the novel features which are believed to be characteristic of this invention will be forming a part hereof, in which:

Fig. 1 is an elevational, side view 7 Fig. 2 is an elevational, front tial elements of the invention.

Fig. 3 is a detailed cross-sectional view of the rewind reel, and

Fig. 4 is an electrical circuit diagram of the starting circuit for the rewind motor used in the invention.

Referring now to the drawings, in which the same numerals identify like elements, a sound view of the essena supply reel l2 and passes through the reproducer in the direction of the arrow around a sprocket 13 having a pad roller I4, around the I5, over a sprocket I6 with a pad roller I1, over a sprocket I8 with a pad roller l9, and around a roller 20 to a take-up reel 22.

other section being attached to the shaft 29, as is well-known in the art.

The supply reel perimeter surface. tapered puck 32 made up of several layers of leather washers, the 54 of a split single phase motor 35. The angle of bevel of the pulley 3! is fifteen de: grees, this pitch preventing lock-in and bounce, lock-in being caused by too fiat an angle, and bounce and lack of driving friction by too great an angle. V

In previous equipments; the large motor 35 was C permanently connected to the pulley 3|, so that as the film was advanced through the projector,

of a film're- I the rotor of the motor was rotated by the pull of the film. Thus, the film tension between the sprocket l3 and the roll of film on the reel l2 was determined by friction and the inertia of the motor armature and other rotating elements. In the present invention, the motor is disconnected from the supply reel, thus a spring loaded pin 31 is mounted in the bracket 38. This pin, being under tension of the spring All, suppliesa hold:

back drag on the film reel, so that the film does not unwind in jerks. Referring now to 3, the rewind motor 35 is shown with its stator coils 50 and its rotor 52 mounted on the shaft 53. v is of a larger diameter than the bearing portions 54, and, as shown in Fig. 3, the shoulder M between the two shaft portions abuts the end bell 420i the motor, while theshoulder-fl i is spaced from the innersurface of the end bell 45. Thus, the shaft 53-5 1 and rotor 52 are movable axially the distance of the space shown between the shoulder s4 and, end bell 45, This amount of movement is sufficient for the puck 32 to make contact with the pulley 3} when the rotor is moved to the left, and to break contact when the rotor is in the position shown in the drawing.

.There is also generally shown at 46 a standard centrifugal butterfly assembly, which urges the rotor to they right when the motor is de-energized.

' This assembly also breaks a contact l'i, one section. of which is mounted on the collar 18 by a bracket 4%. The contact 41 is the starting coil switch for the motor 35.

It is noted from the position of stator plate 55 that the rotor 52, when in its rest position, is not centered with respect to .the stator coils. However, upon energizaticn, the rotor will be pulled to the magnetic center of the coils so, which moves the puclrtZ to the left to make contact with the pulley 3!. After the motor is de-energized, the rotor is returned to the position shown in the drawing, and the puck 32 is disconnected from the driven pulley 3i. Thus, during the reproducing operation, in which the film Sis in the position shown in solid lines in Fig. l, the rotor of the motor 35 is disconnected from the supply reel, and the only holdback friction is the spring loaded pin 31. However, when it is desiredto rewind the film, it is threaded as shown by the dotted line 8,'and the motor 35 is energized, which connects it to the pulley for a rapid rewind of the film.

During the rewinding operation, a mercury switch 6| in an arm 62 pivoted at 63 and having a roller 64 is held in the position'shown by the dotted lines in Fig. l. The energizing circuit of the motor passes through the mercury switch, and, after the end of the film has passed the roller 64, the arm 62 takes the positionshown in the solid lines, and the motor'35 is de-energized.

Fig. lshlows the permanent field winding 50 and the'starting field winding'55, the latter being connected through a switch 41. When the rotor52 accelerates to approximately one- -half full speed, the centrifugal mechanism operates and forces the contacts at 41 to open, thus removing the voltage on starting winding 55 When switch 6! is opened, the rotor 52 coasts'to a stop and the centrifugal mechanism collapses, allowing spring pressure to close switch 41 and also move rotor'52 to the right. This typeof motor control is described in McGraw-Hill Standard Handbookfbr Electrical Engineers, 1949,"Eigh'th Edition, page 742 paragraph 253.

The above rewind'system,"thefefdra fiefiits an The shaft portion :3

operator to quickly rewind the film either partially or completely in a very short time, since not only is the film rewound at a, faster rate by the large motor 35, but fewer manipulations by the operator are required. This is particularly important where one operator is attending several reproducers during the rerecording operation.

I claim:

, .1. A film rewind mechanism comprising means for advancing a film at a comparatively low and a substantially uniform velocity, a reel for supplying said film, a take-up reel for said film, power means for driving said take-up reel, a comparativelylarge motor for driving said supply reel to rewind said thereon at a comparatively high speed, said motor being disconnected from said supply reel as said film is advanced from said supply reel to said take-up reel, and means for automatically connecting said comparatively large motor to said supply reel when said motor is chargized to rewind said film on said supply reel at said comparatively high speed.

2. A film rewind mechanism in accordance with claim 1, which said last mentioned means includes a pulleyfor said supply reel, said pulley having a rim with a taper of approximately fifteen degrees, a puck on the rotor shaft of said motor adapted to be held in driving contact with said pulley by the energy applied to said motor, said puck'having the same taper as said pulley, and bias means to move said puck out of contact with said pulley when said motor is de-energized. 3. A rewind'mecha-nisr'n for film comprising a supply reel for supplying film'at one speed and for rewinding film thereon at a higher speed, a take-up're'el, means for driving said take' up r'eel atfa comparatively low speed when said supply reel is supplying film, a shaft for said supply reel, a "pulley on said shaft, a comparatively large motor for 'rewindi'hg'said film at a comparatively high speed, a rotor for said last mentioned motor, a shaft for said'rotor, said rotor and said shaft therefor being movable axially a predetermined distance, a-puck on said'mtor shaft, said puck contacting said-pulley when said rotor and said rotor shaft are in one position, said puck being separated from "sad pillleiy when "said rotor and said rotor "shaft are in'another position, energizeu n or said meter stationing a e motor and said rotor shaft said first meriti'oned position, and inans'for moving saidro'to'r and said rotor shaft to selid second me tidied "pUSition when said mot'o'r'is de energi'z'ed. I a V "4, A rewind inechaasm in accordance with claim which a movable switch is providedfor said motor, said switch bein'gfheld closed by film passing iramsara take-up reel to said supply r'eel, said seal 'ehed when said film is reinpvejdfriomfs'aid witch. v

5 "A rewind "mechanism in accordance with claim 3, in which said pulley has a'pi'tch of subll'y fifteen degrees on the contact the J and saidpuch has a likepitch on assurfacead plied to contactsaidpulley rim. A

lBlERON F. RYAN. References Cited in the prefer this patent UNITE-l3 STATES'PATE'NTS 

